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authorMaciej W. Rozycki <macro@linux-mips.org>2007-10-23 12:43:25 +0100
committerRalf Baechle <ralf@linux-mips.org>2008-01-29 10:14:55 +0000
commit619b6e18fce20e4b2d0082cde989f37e1be7b3e1 (patch)
treeb56120c0de584f6672aa7e4533163435613f5203 /arch/mips/lib/memset.S
parent20d60d9973c3b441902b0a3f4f6f7e7ade08f77d (diff)
[MIPS] R4000/R4400 daddiu erratum workaround
This complements the generic R4000/R4400 errata workaround code and adds bits for the daddiu problem. In most places it just modifies handwritten assembly code so that the assembler is allowed to use a temporary register as daddiu may now be treated as a macro that expands to a sequence of li and daddu. It is the AT register or, where AT is unavailable or used explicitly for another purpose, an explicitly-named register is selected, using the .set at=<reg> feature added recently to gas. This feature is only used if CONFIG_CPU_DADDI_WORKAROUNDS has been set, so if the workaround remains disabled, the required version of binutils stays unchanged. Similarly, daddiu instructions put in branch delay slots in noreorder fragments are now taken out of them and the assembler is allowed to reorder them itself as possible (which it does making the whole idea of scheduling them into delay slots manually questionable). Also in the very few places where such a simple conversion was not possible, a handcoded longer sequence is implemented. Other than that there are changes to code responsible for building the TLB fault and page clear/copy handlers to avoid daddiu as appropriate. These are only effective if the erratum is verified to be present at the run time. Finally there is a trivial update to __delay(), because it uses daddiu in a branch delay slot. Signed-off-by: Maciej W. Rozycki <macro@linux-mips.org> Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Diffstat (limited to 'arch/mips/lib/memset.S')
-rw-r--r--arch/mips/lib/memset.S11
1 files changed, 10 insertions, 1 deletions
diff --git a/arch/mips/lib/memset.S b/arch/mips/lib/memset.S
index 3f8b8b3d0b2..3bf38422342 100644
--- a/arch/mips/lib/memset.S
+++ b/arch/mips/lib/memset.S
@@ -5,6 +5,7 @@
*
* Copyright (C) 1998, 1999, 2000 by Ralf Baechle
* Copyright (C) 1999, 2000 Silicon Graphics, Inc.
+ * Copyright (C) 2007 Maciej W. Rozycki
*/
#include <asm/asm.h>
#include <asm/asm-offsets.h>
@@ -74,8 +75,16 @@ FEXPORT(__bzero)
bnez t0, small_memset
andi t0, a0, LONGMASK /* aligned? */
+#ifndef CONFIG_CPU_DADDI_WORKAROUNDS
beqz t0, 1f
PTR_SUBU t0, LONGSIZE /* alignment in bytes */
+#else
+ .set noat
+ li AT, LONGSIZE
+ beqz t0, 1f
+ PTR_SUBU t0, AT /* alignment in bytes */
+ .set at
+#endif
#ifdef __MIPSEB__
EX(LONG_S_L, a1, (a0), first_fixup) /* make word/dword aligned */
@@ -106,7 +115,7 @@ memset_partial:
.set noat
LONG_SRL AT, t0, 1
PTR_SUBU t1, AT
- .set noat
+ .set at
#endif
jr t1
PTR_ADDU a0, t0 /* dest ptr */